Two Nevada teens admitted last week to bludgeoning and stabbing their mother to death, and then burying her in a shallow desert grave because they were sick of her “complaining,” according to investigators.

Michael Wilson and Dakota Saldivar, both 17, were arrested July 30 and ordered held without bail after leading investigators to the remote desert area where they allegedly copped to burying their mom, Dawn Liebig, outside Pahrump, Nevada, according to the Nye County Sheriff’s Office.

According to Fox 5 Las Vegas, Wilson told police he was adopted and had lived with Liebig for five years, while it was unknown if Saldivar was adopted or not. The pair have an older brother, Adam Liebig, who was reportedly in jail at the time of the murder, Fox 5 reports.

Police arrived at Liebig’s home last week on a welfare check, after someone in Idaho reported the 46-year-old Liebig missing, according to Fox 5 Las Vegas. Initially, Saldivar and Wilson told investigators that they weren’t sure of their mom’s whereabouts. But the man who phoned in the missing-person report told cops he was suspicious of the teens, and worried that Liebig may already be dead “due to the type of family she is in,” Fox 5 reports.

When police returned on July 30, police interviewed the teens separately and they began to find inconsistencies in their stories, including a text message that Wilson had sent saying “my mother passed away,” according to Fox 5 Las Vegas.

That’s when Liebig’s grim fate became known, Sgt. Adam Tippetts of the Nye County Sheriff’s Department, said in a statement.

“They reported that at her request they stabbed her to death,” Tippetts said.

But as their stories continued to fall apart, the teens came clean, leading police to the spot where they had buried Liebig and disposed of the weapons they allegedly used to kill her, Tippetts said. In a video posted by police on social media, investigators could be seen digging in the rocky soil illuminated by floodlights.

In interviews with police, Wilson and Saldivar told investigators that they were sick of their mom’s demands on them, and had had a fight with her on July 19, hours before her death, Tippetts said.

After she fell asleep, the pair crept up on her and tried to slash her jugular vein in order to kill her quickly, but when Liebig cried out and fought back, they began to bludgeon her with a hammer, police told Fox 5 Las Vegas.

Liebig fought for her life for nearly 30 minutes until the boys finally managed to subdue her by crushing her skull, Tippetts said.

On her Facebook profile, Liebig’s biography reads as a tragic message of love for her children.

“im a mom that hopes she did okay.i want my boys to become the men i hoped for.i live for them [sic],” the profile reads.

After their arrest, the boys told police that they had to return home to care for the more than 20 cats, some of them visibly emaciated, that were living on the property, according to Fox 5 Las Vegas.

Instead, Saldivar and Wilson were booked at the Nye County Detention Center where they were charged as adults with murder, conspiracy to commit murder, and domestic battery with a deadly weapon, police said.

They were ordered held without bail and are due back in court on Aug. 9, according to Fox 5 Las Vegas.